Field of the Invention
The present invention relates to a solid-state image sensor, a method of manufacturing the same, and a camera.
Description of the Related Art
Japanese Patent Laid-Open No. 2009-26848 describes a solid-state image sensor which includes a sensor area (pixel area) forming a pixel portion and a MOS transistor area (peripheral circuit area) forming a CMOS logic circuit portion, and a method of manufacturing the same. This manufacturing method includes a step of forming a silicon oxide film and a silicon nitride film in order on a substrate where gate electrodes have been formed, and a step of etching the silicon oxide film and the silicon nitride film. With this etching, side wall spacers are formed simultaneously on the side faces of the gate electrodes in both the sensor area and the MOS transistor area. Japanese Patent Laid-Open No. 2011-243747 describes a photoelectric conversion device which includes a pixel area and a peripheral circuit area. This photoelectric conversion device includes side spacers on the side faces of the gate electrodes in both the pixel area and the peripheral circuit area. Note that the words “side wall spacer” and “side spacer” are synonymous.
In the method described in Japanese Patent Laid-Open No. 2009-26848, the silicon oxide film and the silicon nitride film are formed in the sensor area and the MOS transistor area, and then the silicon oxide film and the silicon nitride film in the sensor area and the MOS transistor area are etched simultaneously. Therefore, in the method described in Japanese Patent Laid-Open No. 2009-26848, the side wall spacer formed in the sensor area (pixel area) and the side wall spacer formed in the MOS transistor area (peripheral circuit area) have the same shape. In a method of etching an insulating film in the sensor area and an insulting film in the MOS transistor area simultaneously, it may be difficult to optimize components in the sensor area (pixel area) and components in the MOS transistor area (peripheral circuit area) separately. Note that the components can be, for example, photoelectric converters, light transmission units positioned on the photoelectric converters, MOS transistors, and the like. Furthermore, optimization of the components can include, in addition to optimization of the characteristics of the components, facilitation of a step of forming the components or the like.
Japanese Patent Laid-Open No. 2011-243747 does not specifically disclose what kind of a procedure is used to manufacture the side spacer in the pixel area and the side spacer in the peripheral circuit area.